Stroke increasing system for jacks



Oct. 18, 1966 HENRPJEAN DAUBRESSE 3,279,854

STROKE INCREASING SYSTEM FOR JACKS Filed Dec. 9, 1964 United States Patent y p Filed Dec. 9, 1964, Ser. No. 417,191

Claims priority, application France, Dec. 11, 1963,

56,87 3 Claims. (Cl. 29822) The present invention has for its object a stroke increasing system for jacks adapted for instance to form the raising means for a pivoting vehicle body.

The object of the invention is to constitute such a system which allows lifting over a large distance without resorting to a jack of the multiple expansion type.

The invention has furthermore for its object to solve the problem of housing under minimum bulk conditions, the complete lifting mechanism extending between the body and the chassis of the carrier vehicle when said mechanism is inoperative.

The stroke increasing system for jacks fitted between two members to be shifted away from each other includes, according to the invention, on the one hand two arms each of which is pivotally secured through one of its ends with the corresponding member while its other end is pivotally secured to the corresponding ends of a pair of connecting links and, on the other hand, said system includes a jack of which the extreme components are pivotally secured to the corresponding arms at an intermediate point of their length.

The invention will be readily understood from the following specification, reference being made to the accompanying drawings wherein:

FIGS. 1 and 2 illustrate, with certain parts removed, a pivoting body provided with a system according to the invention, said FIGS. 1 and 2 showing said body respectively in its transportation position and in its raised position,

FIG. 3 is a perspective view of the novel system in a position of partial expansion, the frame to which the body is pivotally secured not being illustrated for sake of clarity.

Said figures show a truck or lorry including a chassis C the rear end of which carries bearing members 1 in which an intermediate frame F carrying the body B is adapted to rock about the transverse axis a.

To the chassis C is secured, preferably in an area located ahead of the center of gravity of the load carried by the body, a strap 2 inside which the end of a lower arm 3 is pivotally secured about an axis b. Similarly, the upper arm 4 of the system is pivotally secured about an axis d to a strap 5 rigid with the body frame F.

Each of the arms 3, 4 includes two flanges shown at 3a-3b and 4a-4b between which extend the corresponding axes f and g to which the respective ends 7a, 7b of the cylinder and of the piston rod of the hydraulic jack 7 are pivotally secured.

The arms 3 and 4 are interconnected by the pair of parallel links 6a, 6b pivotally secured to said arms about the corresponding axes e, 2'.

It should be remarked that the pivotal axes f, g, to

which the ends of the jack are connected, lie outside the lines connecting the terminal pivotal connections b, e on the arm 3 and e, d on the arm 4, respectively.

The jack 7 is connected in a conventional manner, not shown, with a pump through yielding conduits which provide for the input and output of liquid under pressure.

The members forming the system are designed and sized in a manner such that when the body is in its inoperative collapsed position as illustrated in FIG. 1, the axes b and d are substantially in near vertical registry with each other, the arms 3 and 4 extending then substantially along horizontal lines facing opposite directions, that is forwardly of the axis d for the arm 4 and rearwardly of its axis 12 for the arm 3.

FIG. 1 shows that for such a collapsed position of the system, the simple expansion jack 7, in spite of its comparatively considerable length, is housed readily between the body and the chassis in an approximately horizontal plane.

When the pressure of the liquid is applied to said jack, the piston rod -7 b expands outwardly and causes a pivotal movement of the arms 3 and 4 about the corresponding pivotal connections e, e through which each of said arms is connected with the ends of the links 6a, 6b.

The whole system opens thus symmetrically with reference to said links, as illustrated clearly in FIGS. 2 and 3.

In the system described, a suitable selection of the ratios between the lever arms of the arms 3 and 4 defined by the three points of application of the forces on the three axes provided on each arm, allows obtaining, as illustrated in FIG. 2, a very large coeflicient of multiplication of the stroke executed by the expanding element of the jack. This property of the system allows shifting clearly to the front of the center of gravity of the load of the body, the pivotal connection d and consequently, the pivotal connection b between the chassis and the arm 3. This is of particular interest since it allows reducing the Weight of the structure which is subjected only to a limited stress at the point of application of the weight of the body.

Obviously, the invention is by no means limited to the embodiment described and it is possible for instance to resort to a stroke increasing system for a body adapted, in the conventional manner, to pivot selectively to the rear or laterally to either side of the vehicle.

What I claim is:

1. A device for changing the relative angular position of two members interconnected by pivotal joint means comprising, two oppositely directed arms one of which being pivotally connected to one of said members spaced from said joint means, the other of which being pivotally connected to the other of said members spaced from said joint means, a rigid elongated link pivotally and spacedly interconnecting the free ends of said arms and elongated expandable power means, one end of said power means being pivotally connected to one of said arms at a location intermediate of its pivotal connection with one of said members and its pivotal connection with said link, the other end of said power means being pivotally connected to the other of said arms at a location intermediate of its pivotal connection with the other of said members and its pivotal connection with said link.

2. A device as defined in claim 1, wherein one of said References Cited by the Examiner members constitutes the chassis of a vehicle, the other UNITED STATES PATENTS of said members constitutes the body of said vehlcle.

3. A device as defined in claim 1, wherein said loca- 2,836,460 5/1958 Lunfiiell 298 2 tions of pivotal connections between said power means 5 3,210,120 10/1965 Gown 298-4 and each of said arms lies outside of a line that extends FOREIGN PATENTS through the pivotal connections of each of said arms 790073 9/1935 France with said link and With said members, said arms maintaining a symmetrical position With respect to the length BENJAMIN HERSH, Primary Examiner dimension of said power means In any angular position 10 R. I JOHNSON Assistant Examiner said members may assume during operation. 

1. A DEVICE FOR CHANGING THE RELATIVE ANGULAR POSITION OF TWO MEMBERS INTERCONNECTED BY PIVOTAL JOINT MEANS COMPRISING, TWO OPPOSITELY DIRECTED ARMS ONE OF WHICH BEING PIVOTALLY CONNECTED TO ONE OF SAID MEMBERS SPACED FROM SAID JOINT MEANS, THE OTHER OF WHICH BEING PIVOTALLY CONNECTED TO THE OTHER OF SAID MEMBERS SPACED FROM SAID JOINT MEANS, A RIGID ELONGATED LINK PIVOTALLY AND SPACEDLY INTERCONNECTING THE FREE ENDS OF SAID ARMS AND ELONGATED EXPANDABLE POWER MEANS, ONE END OF SAID POWER MEANS BEING PIVOTALLY CONNECTED TO ONE OF SAID ARMS AT A LOCATION INTERMEDIATE OF ITS PIVOTAL CONNECTION WITH ONE OF SAID MEMBERS AND ITS PIVOTAL CONNECTION WITH SAID LINK, THE OTHER END OF SAID POWER MEANS BEING PIVOTALLY CONNECTED TO THE OTHER OF SAID ARMS AT A LOCATION INTERMEDIATE OF ITS PIVOTAL CONNECTION WITH THE OTHER OF SAID MEMBERS AND ITS PIVOTAL CONNECTION WITH SAID LINK. 